Recent advances in minimally invasive surgical techniques, such an endoscopy, laparoscopy and arthroscopy, have made it possible for complex surgical techniques to be performed with minimal disruption and cutting of tissue. These techniques are performed using various types of scopes which allow the surgeon to visualize the operative site. The scopes and instruments are designed to be inserted through trocar cannulas which are positioned about the operative site using trocar knives or obturators. The trocar obturators produce minimal punctures when inserted into a body cavity or joint. The body cavity or joint is typically insufflated or expanded with a biocompatible gas or liquid, such as carbon dioxide or sterile saline solution in order to provide the surgeon with room to conduct the surgical procedure.
In most surgical procedures, tissue must be approximated to repair wounds and tears and to close incisions. There are numerous known methods and devices for approximating tissue. The devices include surgical needles, surgical sutures, staples and the like. It is also known to use surgical tacks and other fasteners. One particular type of fastener which is known is an "H-shaped" fastener. H-type fasteners and methods of use are disclosed in U.S. Pat. Nos. 4,006,747 and 4,586,502 which are incorporated by reference. The H-type fastener typically has a central connecting section having opposed ends with tissue anchor members mounted to each end. H-type fasteners and fastening systems for non-medical use are commonly used to affix labels and tags to clothing.
The H-type fasteners may have advantages over conventional fasteners in certain minimally invasive techniques. In particular, it is known to use H-type fasteners in arthroscopic techniques such as meniscal repair as disclosed in U.S. Pat. No. 5,320,633. Damage to the meniscus, such as rips or tears, has been found to be repairable if the torn pieces of the meniscus are approximated. At one time, the prevailing practice was such that the torn sections of the meniscus would be surgically removed, eventually resulting in damage to the bones in the joint caused by bone-on-bone contact. Presently, however, it has been found that, in order for the meniscal repair to be effective, the opposing surfaces of the torn or ripped meniscus must be approximated such that the surfaces are maintained in close contact.
The H-type fasteners are believed to be effective in meniscal repair since they are relatively easy to insert using a conventional apparatus having a cannulated distal needle wherein the needle has a longitudinal slot. One leg or tissue anchor of the H-type fastener is loaded into the cannulated needle, preferably having a slot. The needle is inserted through both sides of the meniscal tear and one leg or anchor is expelled from the needle on one side of the tear. The needle is then removed from the meniscus and the other opposed leg or anchor remains in place positioned on the opposite side of the tear, thereby approximating the meniscal tear.
There are certain disadvantages associated with the use of existing H-type fasteners to approximate a tear in a meniscus. One disadvantage is that the surgeon must precisely measure the meniscus prior to inserting the H-type fastener in order to select the proper size H-type fastener. A precise measurement is necessary because the fastener must be sized to approximate and compress the opposing sides or surfaces of the tear against each other. One skilled in the art will appreciate the difficulties involved in attempting to obtain such measurements during an arthroscopic or minimally invasive procedure in which a scope is used. Even if a precise measurement is possible and an appropriately sized H-type fastener is utilized, proper tissue approximation is difficult to accomplish since it is often impossible to precisely place a needle in a meniscus, in vivo, especially during an arthroscopic procedure. Consequently, the meniscus is often under-approximated with inadequate face-to-face contact, or over-approximated with inadequate face-to-face contact. In addition, there are only a limited number of sizes of H-type fasteners which the surgeon will typically have available during an operative procedure, further complicating the surgical procedure and the obtention of adequate tissue to tissue contact in the repaired meniscus. As alluded to above, the surgeon must precisely choose the size of the H-type fastener. If the H-type fastener selected by the surgeon is too large, there will be no tissue approximation. If the H-type fastener is too small, the tissue may fold and bunch, possibly turning the edges or surfaces of the tear so that they are not in contact with each other, thereby effecting only a partial or inadequate repair.
What is needed in this art are improved H-type surgical fasteners for approximating tissue which overcome the disadvantages associated with the H-type fasteners of the prior art.